1. Field of the Invention
Embodiments relate to a protective circuit board, a battery pack, and associated methods. More particularly, embodiments relate to a protective circuit board, a battery pack, and a method of fabricating the same, in which an electrical connection structure between an electrode tab of a bare cell and a lead terminal of a protective circuit board is configured so that a plurality of electrode tabs may be electrically connected to the lead terminal at the same time and bond strength between the electrode tab and the lead terminal can be improved.
2. Description of the Related Art
Development and manufacturing of portable electric/electronic devices that are compact in size and light in weight, e.g., cellular phones, notebook computers, camcorders, etc., are actively progressing. Portable electric/electronic devices may include battery packs so that they operate even in places where power is not supplied. The secondary battery is largely classified into a nickel-cadmium (Ni—Cd) battery, a nickel-metal hydride (Ni-MH) battery, and a lithium-ion (Li-ion) secondary battery.
The lithium ion secondary battery has an operating voltage three times higher than that of the Ni—Cd battery or Ni-MH battery, and has high energy density per unit weight, so that it is widely used for a battery pack in portable electronic/electric devices. The lithium ion secondary battery may be classified into a lithium ion battery using a liquid electrolyte and a lithium polymer battery using a polymer electrolyte, depending on the type of an electrolyte to be used. Also, the lithium ion secondary battery may be classified into a prismatic type, a cylindrical type, and a pouch type battery, according to the fabricated shape.
Generally, a battery pack using a lithium ion secondary battery may include a bare cell including an electrode assembly, and a case accommodating the electrode assembly and an electrolyte that enables lithium ions to migrate between the electrode assemblies, and a protective circuit board electrically connected to the bare cell to control voltage or current when the bare cell is charged or discharged.
The electrical connection between the bare cell and the protective circuit board may be achieved by electrically connecting a positive electrode tab and a negative electrode tab, which are electrically connected to the positive electrode plate or the negative electrode plate of the electrode assembly, to the lead terminal of the protective circuit board using welding. Also, since the positive electrode plate and the negative electrode plate may be formed of different materials from each other, in order to maximize efficiency of the bare cell, the positive electrode tab and the negative electrode tab, may also be formed of different conductive materials from each other.
In order to electrically connect the positive electrode tab and the negative electrode tab, which may be formed of different conductive materials from each other, to the electrode terminal of the protective circuit board, a process of electrically connecting the positive electrode tab to the electrode terminal of the protective circuit board, and another process of electrically connecting the negative electrode tab to the electrode terminal of the protective circuit board should be respectively performed. This may cause yield and process efficiency to deteriorate, and bond strength between the positive and negative electrode tabs and the electrode terminal to also deteriorate.